CN113153446B - Turbine guider and centripetal turbine with high expansion ratio - Google Patents
Turbine guider and centripetal turbine with high expansion ratio Download PDFInfo
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- CN113153446B CN113153446B CN202110405459.XA CN202110405459A CN113153446B CN 113153446 B CN113153446 B CN 113153446B CN 202110405459 A CN202110405459 A CN 202110405459A CN 113153446 B CN113153446 B CN 113153446B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D9/00—Stators
- F01D9/02—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles
- F01D9/04—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles forming ring or sector
- F01D9/041—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles forming ring or sector using blades
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/08—Cooling; Heating; Heat-insulation
- F01D25/12—Cooling
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D9/00—Stators
- F01D9/02—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles
- F01D9/04—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles forming ring or sector
- F01D9/045—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles forming ring or sector for radial flow machines or engines
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- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
Abstract
The invention discloses a turbine guider and a centripetal turbine with a large expansion ratio, wherein the turbine guider comprises a guider outer ring, a guider inner ring and a plurality of guider blades, the guider outer ring and the guider inner ring are symmetrically arranged around the axis of an engine, an annular airflow channel is formed between the guider outer ring and the guider inner ring, the annular airflow channel is folded in a 90-degree direction after a certain length of the annular airflow channel is axially extended at the inlet of the centripetal turbine and then forms airflow channels distributed along the radial direction, the plurality of guider blades are uniformly distributed in the annular airflow channel at the same intervals along the circumferential direction, the ratio of the height of an inlet straight section of each guider blade to the height of the inlet of each blade is designed to be 1.15-1.25, and the radius ratio of the inlet and the outlet of each guider blade is 1.1-1.3. The invention can effectively reduce the outer diameter size of the whole guider by reducing the height of the straight section of the inlet of the guider and reducing the radius ratio of the inlet to the outlet of the guider blade. Thereby reducing the weight of the turbine and improving the power-to-weight ratio of the engine.
Description
Technical Field
The invention relates to the technical field of centripetal turbine guider design, in particular to a turbine guider and a centripetal turbine with a large expansion ratio by adopting the turbine guider.
Background
In view of compact structure, the core structure layout of a centrifugal compressor, an annular backflow combustion chamber and a centripetal turbine is generally adopted in small-sized gas turbine engines and aviation auxiliary power devices. A current trend of gas turbine engines is to gradually develop to higher power-to-weight ratio and higher thermodynamic cycle parameters, and in order to increase the output power of the engine and reduce the weight of the engine, the temperature before the turbine and the expansion ratio of the single-stage turbine are continuously increased. For a single-stage centripetal turbine with the expansion ratio exceeding 4.0, the turbine guider and the impeller flow channel can be in a supersonic flow state, and strong shock waves exist in a turbine blade grid channel; meanwhile, the increase of the front temperature of the turbine exceeds the temperature bearing limit of a guider material, and the turbine guider needs to be cooled, but due to the arrangement of a cooling structure, on one hand, the blade profile and the trailing edge thickness of the guider blade are increased, so that the increase of the wake and the friction loss is caused, and on the other hand, supersonic shock wave loss and cold air mixing loss exist in a guide vane cascade channel, so that the change of guide vane outlet parameters is severe, the intensity of secondary flow in the cascade channel is increased, the secondary flow loss of the guide vane is relatively large, and the improvement of the turbine efficiency is influenced. Therefore, the current centripetal turbine guider usually adopts a non-cooling design, and in order to prevent the temperature from exceeding the temperature bearing limit of the guider material, the maximum temperature before the turbine is reduced, but the improvement of the power-weight ratio of the engine and the use range are influenced.
In addition, because of the radial flow characteristics of the centripetal turbine airflow, the radial height of the inlet of the guider is generally the maximum outer diameter dimension of the whole centripetal turbine, and in order to reduce the weight of the turbine and meet the requirement of the size of an interface with a backflow combustion chamber, the radial dimension of the guider is generally expected to be reduced, so that the requirements of reducing the radial height of the centripetal turbine and reducing the weight of the turbine are met. However, the reduction of the radial size of the guider can cause the increase of the mach number of the incoming flow of the inlet, thereby causing the increase of the loss of the cascade channel; in addition, the load of the vane of the guider is increased, and the design difficulty of the guider is increased. Therefore, the existing guider of the radial inflow turbine usually adopts a design with a large outer diameter and a large blade chord length, so that the turbine has high overall dimension and heavy weight, the molded line of an inlet runner of the guider is not optimized, flow separation exists at the corner, and the flow loss is large. In addition, the single-stage expansion ratio of the existing centripetal turbine is not high, the flow in the guider is subsonic flow, the acceleration capability of the airflow is low, and the work doing capability of the centripetal impeller is influenced.
Disclosure of Invention
The invention provides a turbine guider and a centripetal turbine with a large expansion ratio, which are used for solving the technical problem that the existing turbine guider is large in radial size and low in power-weight ratio of an engine.
According to one aspect of the invention, the turbine guider is applied to a centripetal turbine with a large expansion ratio and comprises a guider outer ring, a guider inner ring and a plurality of guider blades, wherein the guider outer ring and the guider inner ring are symmetrically arranged around an engine axis, an annular airflow channel is formed between the guider outer ring and the guider inner ring, the annular airflow channel is folded in a 90-degree direction after a centripetal turbine inlet extends for a certain length along the axial direction to form airflow channels distributed along the radial direction, the plurality of guider blades are uniformly arranged in the annular airflow channel at the same interval angle along the circumferential direction, the ratio of the height of an inlet straight section of each guider blade to the height of a blade inlet is designed to be 1.15-1.25, and the radius ratio of an inlet and an outlet of each guider blade is designed to be 1.1-1.3.
Further, the outer ring of the guide has an outwardly convex bulge-like structure at the position when turned axially to the radial direction to ensure a gradual expansion of the annular passage area from the guide inlet to the leading edge of the guide vane.
Furthermore, a cold air cavity is arranged in the guide vane, and a plurality of cold air slits are arranged at the tail edge of the guide vane in a 10% -90% vane height area.
Further, the position on the blade basin surface of the guide blade from the trailing edge of the guide blade to 16.5% of the whole chord length is the starting position of the cold air slit.
Further, the guide vane is designed to be a uniform-section vane type.
Furthermore, the guide vane adopts a contracting vane profile design, and the throat width of the vane is positioned between the trailing edge of the guide vane and the throat position of the vane back face of the adjacent vane.
Further, the bending angle delta of the tail edge of the guide vane is between 1 and 16 degrees.
Further, the vane profile of the guide vane has a maximum thickness C max The ratio to the chord length b of the blade is 0.17.
Further, the relative thickness R of the trailing edge of the guide vane t Is 0.1C max 。
In addition, the invention also provides a centripetal turbine which adopts the turbine guider.
The invention has the following effects:
the turbine guider comprises a guider outer ring, a guider inner ring and a plurality of guider blades, wherein the guider outer ring and the guider inner ring are symmetrically arranged around the axis of an engine, an annular airflow channel is formed between the guider outer ring and the guider inner ring, the annular airflow channel is folded in the 90-degree direction to form airflow channels distributed along the radial direction after extending for a certain length along the axial direction of an inlet of a centripetal turbine, the plurality of guider blades are uniformly arranged in the annular airflow channel at the same interval angle along the circumferential direction, the ratio of the height of an inlet straight section of each guider blade to the height of a blade inlet is designed to be 1.15-1.25, and the radius ratio of the inlet and the outlet of each guider blade is 1.1-1.3. The turbine guider can effectively reduce the outer diameter size of the whole guider by reducing the height of the straight section of the inlet of the guider and reducing the inlet-outlet radius ratio of the blades of the guider. Thereby reducing the weight of the turbine and improving the power-to-weight ratio of the engine.
In addition, the centripetal turbine with a large expansion ratio according to the present invention also has the above-described advantages.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic view of the overall structure of a turbine nozzle according to a preferred embodiment of the present invention.
Fig. 2 is a partial structural view of a turbine nozzle according to a preferred embodiment of the present invention.
Fig. 3 is a schematic view of the dimensional design of the turbine nozzle in the meridian flow plane of a centripetal turbine according to a preferred embodiment of the present invention.
FIG. 4 is a meridional flow surface schematic of a turbine nozzle of a preferred embodiment of the invention.
FIG. 5 is a schematic view of a flow field within a prior art turbine vane.
FIG. 6 is a schematic view of the flow field within a turbine vane of a preferred embodiment of the present invention.
Fig. 7 is a schematic structural view of a guide vane of a preferred embodiment of the present invention.
FIG. 8 is a schematic view of the airfoil of a preferred embodiment of the present invention.
Fig. 9 is a structural schematic view of a centripetal impeller of a high expansion ratio turbine in accordance with another embodiment of the present invention.
Figure 10 is a schematic representation of a meridional structure of a high expansion ratio turbine according to another embodiment of the invention.
FIG. 11 is a two-dimensional schematic representation of a flow surface airfoil in M-theta space according to another embodiment of the present invention.
Fig. 12 is a schematic diagram of a three-dimensional space curve presented by a flow surface blade profile in a cartesian coordinate system according to another embodiment of the invention.
FIG. 13 is a schematic illustration of a comparison of a low solidity blade design with a conventional design in another embodiment of the invention.
FIG. 14 is a schematic view of a flow angle profile at a blade tip in another embodiment of the present invention.
FIG. 15 is a schematic diagram comparing a blade stack design of a low solidity impeller with a conventional design in another embodiment of the invention.
Description of the reference numerals
1. A deflector outer ring; 2. a guide inner ring; 3. a guide vane; 31. a guide vane leading edge; 32. a guide vane trailing edge; 33. a leaf basin surface; 34. the back of the leaf; 35. a cold air slit; 36. a cascade channel; 37. a cold air cavity; 5. a wheel disc; 6. an impeller blade; 61. an impeller blade leading edge; 62. the trailing edge of the impeller blade; 63. a blade root; 64. a blade tip portion; 7. a flow surface leaf profile; 8. stacking lines; 71. a blade back profile; 72. a leaf basin molded line; 73. a mean camber line; 74. a profile leading edge; 75. the trailing edge of the blade profile.
Detailed Description
The embodiments of the invention will be described in detail below with reference to the accompanying drawings, but the invention can be embodied in many different forms, which are defined and covered by the following description.
As shown in fig. 1 and 2, a preferred embodiment of the present invention provides a turbine nozzle, which is applied to a radial inflow turbine with a large expansion ratio, and includes a nozzle outer ring 1, a nozzle inner ring 2, and a plurality of nozzle blades 3, wherein the nozzle outer ring 1 and the nozzle inner ring 2 are symmetrically arranged around an engine axis, an annular gas flow passage is formed between the nozzle outer ring 1 and the nozzle inner ring 2, and the plurality of nozzle blades 3 are uniformly arranged in the annular gas flow passage at the same interval angle in a circumferential direction. The annular airflow channel is in an inverted L shape in side view, namely the annular airflow channel extends to a certain length along the axial direction of the inlet of the centripetal turbine and then turns 90 degrees to form airflow channels distributed along the radial direction. In order to meet the requirements of air flow acceleration and deflection, the number of the guide vanes 3 is 12-45 according to the cycle parameters of an engine, and preferably, 23 guide vanes 3 are selected. In addition, the outer guider ring 1, the inner guider ring 2 and the plurality of guider blades 3 can be processed in an integral casting mode, or can be processed in a single piece and then welded into a whole. The guide vane 3 includes a guide vane leading edge 31, a guide vane trailing edge 32, a blade basin surface 33 and a blade back surface 34, a blade cascade channel 36 is formed between the blade basin surfaces 33 and the blade back surfaces 34 of two adjacent vanes, and the airflow circulates in the blade cascade channel 36.
As shown in FIG. 3, the maximum outer diameter of the centripetal turbine is defined as r s Then r is s ＝r 1 +h 1 Wherein r is 1 Is the value of the radius at the leading edge 31 of the guide vane, h 1 The height of the straight section of the guide entrance. The invention achieves the purpose of reducing the radial height r of the centripetal turbine by two means s Further, the aims of reducing the height of the centripetal turbine and the weight of the turbine are fulfilled. First is to reduce h 1 Defining the height of the inlet of the blade as h, the invention designs h 1 Has a/h of between 1.15 and 1.25, preferably 1.2, and is knownThe ratio of the guide vanes to the guide vane is basically 1.3-1.6, so that the design space of the guide vane 3 is ensured, the height of the straight section of the guide vane inlet is reduced, and the radial size of the guide vane is reduced. Second, reducing axial chord length b of blade x The value of the radius at the position of the trailing edge 32 of the guide vane of the guide is defined as r 3 Axial chord length b of the vane x ＝r 1 -r 3 . Radius value r at the location of the trailing edge 32 of the guide vane of a typical guide 3 Is determined by the inlet radius value of the centripetal vane wheel, and r is determined on the premise of not changing the size of the vane wheel 3 Can be considered a constant value, so if the vane axial chord b is to be reduced x At r 3 In certain cases, the radius value r at the leading edge 31 of the guide vane can only be reduced effectively 1 The invention designs the inlet-outlet radius ratio r of the guide vane 1 /r 3 Between 1.1 and 1.3, preferably 1.1, whereas in the prior art guides this ratio is substantially between 1.35 and 1.45. The invention can effectively reduce the outer diameter size of the whole guider by reducing the height of the straight section of the inlet of the guider and reducing the radius ratio of the inlet to the outlet of the guider blade. Thereby reducing the weight of the turbine and improving the power-to-weight ratio of the engine.
As shown in fig. 4, due to the height h of the straight section of the guide entrance 1 This reduction in the inlet annular passage area of the guide vanes 3 reduces and the gas flow mach number increases, which results in flow separation at the corners of the annular flow passage and increased flow losses in the guide. Therefore, the profile of the outer ring 1 of the guider is optimally designed, and the profile of the outer ring in an outward convex mode is adopted. In particular, the outer ring 1 of the guide vane has an outwardly convex bulge-like structure when turned from the axial direction to the radial direction, so as to ensure a gradual expansion of the annular passage area from the guide vane inlet to the guide vane leading edge 31, i.e. a 1 ＜A 2 ＜A 3 . As shown in FIGS. 5 and 6, the invention designs the convex structure at the axial rotation radial position of the outer ring 1 of the guider, thereby effectively reducing the airflow speed at the inlet of the blades 3 of the guider, reducing the flow separation loss at the corner caused by too high flow speed, and increasing the airflow resistance at the cornerSeparation capacity.
As shown in fig. 7 and 8, the present invention also performs a cooling structure design for the vane 3, so that the temperature before the turbine can be greatly increased without worrying about exceeding the temperature bearing limit of the vane material, which is beneficial to improving the power-to-weight ratio of the engine. Specifically, the guide vanes 3 are of uniform cross-section profile design, i.e., the profile cross-sectional shape is uniform along the height of the vane, so as to facilitate the arrangement of impingement cooling holes (not shown) inside the vane. Specifically, a cold air cavity 37 is arranged in the guide vane 3, a plurality of cold air slits 35 for cold air to flow out are arranged at the tail edge 32 of the guide vane in a 10% -90% vane height area, the number of the cold air slits 35 is generally determined by the vane height and the cold air flow, generally, the number is between 4 and 9, and the design of 4 to 5 cold air slits 35 is selected. In addition, the guide vane 3 of the invention also adopts a contraction vane profile design, and the width of the cascade channel 36 is the minimum part, namely the vane throat width a 2 Between the guide vane trailing edge 32 and the point P of the vane back face 34 of the adjacent vane (i.e., the vane throat position), so that the area of the cascade channel 36 always decreases gradually in the gas flow direction, i.e., a 1 ＞a 2 . With the design, after the airflow enters the blade grid channel 36 of the guider, the flow speed is increased all the time before reaching the blade throat and reaches the critical Mach number at the throat, and then after the airflow flows out of the blade throat, the airflow can continue to expand and accelerate at the position of the oblique notch due to the sudden increase of the flow area, and finally the Mach number of the airflow when the airflow enters the front edge of the downstream rotor blade can reach about 1.1. The Mach number of the outlet of the guider is high, the working capacity of airflow can be improved, and the output work of the centripetal turbine can be increased, so that the working capacity of the turbine can be increased based on the design, and the guide vane is well suitable for the centripetal turbine with the expansion ratio of 4.0.
On the other hand, to reduce the profile flow losses at high Mach numbers, the profile at the blade back 34 of the present invention has a smaller change in curvature after the point p at the throat location, and is nearly a straight design. Specifically, the bending angle δ of the trailing edge is used to represent the bending degree of the blade profile of the blade back 34 of the blade, δ is defined as the included angle between the tangent line passing through the point p and the extension line of the tangent point of the trailing edge 32 of the guide blade, specifically, as shown in fig. 8, δ is between 1 ° and 16 °, and the larger the value, the larger the bending degree of the blade back profile is. In this embodiment, δ is 5 °.
The cold air slit 35 of the present invention is formed by partially modifying the trailing edge 32 of the guide vane according to the requirements of the cold air outlet flow rate and the structural strength of the trailing edge 32 of the guide vane, on the basis of the two-dimensional blade profile of the vane. Specifically, the position on the vane bowl surface 33 from the guide vane trailing edge 32 to a% of the entire chord length is positioned as position D, i.e., the position on the guide vane trailing edge 32 where the cold air slit 35 starts. The larger the value a, the larger the cold air influence area, which is detrimental to aerodynamic performance and blade strength, while the smaller the value a, the closer the outlet position of the cold air slit 35 is to the trailing edge where the blade thickness is smaller, the less easy the arrangement of the cold air slit 35. Therefore, the present invention preferably designs a to 16.5. Meanwhile, in order to meet the design of the cooling mechanism inside the blade, namely the design of the cold air cavity 37, a reasonable blade profile thickness design is adopted. The profile thickness is typically determined by making a perpendicular line from any point on the back 34 to the bowl 33, defining the length of the perpendicular line connecting the back 34 and the bowl 33 as the thickness of the blade profile, and defining the maximum profile thickness C max The ratio to the chord length b of the blade is defined as the relative thickness. In this embodiment, the relative thickness C is taken max And/b is 0.17. In addition, the thickness of the trailing edge 32 of the guide vane is too small, the wall thickness cannot be ensured, the cold air slits 35 cannot be arranged, and the larger the thickness is, the larger the trailing edge outlet loss is, and the aerodynamic efficiency is low. Thus, the relative thickness R of the trailing edge 32 of the guide vane is taken into account in the present invention t ＝0.8C max ～1.2C max Preferably 0.1C max . With this design, it is convenient to design the blade cooling structure on the one hand, and wake and friction loss are also reduced on the other hand.
In addition, another embodiment of the invention also provides a high expansion ratio centripetal turbine which adopts the turbine guider, in particular, the high expansion ratio centripetal turbine comprises the turbine guider and a centripetal impeller.
For a centripetal turbine with a large expansion ratio, because the turbine load is greatly improved along with the increase of the expansion ratio, a common centripetal turbine with a large expansion ratio usually adopts a high-consistency impeller design, the work capacity of the impeller is increased by improving the axial length or the number of blades of the impeller, so that the purposes of reducing the blade load on a unit area and improving the efficiency level of the turbine are achieved, but the weight of the impeller is increased due to the design, and the weight of the centripetal impeller usually accounts for about 50% of the weight of the whole centripetal turbine, so that the work-weight ratio of the whole engine is inevitably influenced by the higher consistency of the blades of the impeller. Therefore, on the premise of ensuring that the performance of the turbine is not reduced, the invention adopts the design of the low-consistency impeller, reduces the number of the impeller blades, the axial size and the whole weight of the impeller by selecting the consistency coefficient of the impeller far lower than the conventionally selected consistency coefficient, simultaneously reduces the problems of greatly increased load and increased flow loss caused by the improvement of the expansion ratio and the reduction of the consistency of the turbine by the optimized design of the impeller blade profile, realizes the high-efficiency and high-compactness design of the centripetal impeller with the large expansion ratio, and improves the power-weight ratio of the engine.
Specifically, as shown in fig. 9 to 15, the centripetal impeller is composed of a wheel disk 5 and a plurality of impeller blades 6, the impeller blades 6 are uniformly arranged on the wheel disk 5 along the circumferential direction, and the impeller blades 6 and the wheel disk 5 are formed by integral casting or welding after being manufactured separately. The impeller blade 6 is composed of an impeller blade front edge 61, an impeller blade tail edge 62, a blade root 63 and a blade tip 64, and the impeller blade 6 can be a solid blade or a hollow blade with a cooling channel inside. The blade consistency is mainly the blade spacing between rotor blade units according to the conditions of upstream and downstream rotational flow, which is determined according to the experience of designers and the characteristics of flow loss under the condition of a given inlet flow, and generally, the smaller the blade consistency is, the smaller the blade number of the impeller is, the more compact the impeller structure is, the smaller the size is, and the lighter the weight is, but meanwhile, the blade consistency is reduced, the average load of the blade body is increased, the flow loss is improved, and adverse effects are brought to the aerodynamic performance. Thus, high expansion ratio centripetal turbines currently typically employ high solidity impeller designs.
For centripetal impellers, the blade solidity factor is generally defined as:
Solidity＝ZL ms /d 4 (1)
wherein Z is the number of rotor blades (i.e., the number of impeller blades 6), L ms Is the mean chord length of the blade surface, d 4 Is the impeller blade inlet diameter.
For a centripetal turbine with a large expansion ratio, the diameter of the impeller inlet usually represents the work-doing capacity of the turbine under the condition of a certain rotating speed, so that the diameter value is basically not changed. Therefore, the aim of designing the low-consistency impeller can be achieved by selecting reasonable blade chord length and blade number. The value of the consistence coefficient of the centripetal turbine is 5.0-8.0 generally, but in the invention, the consistence coefficient of the impeller can be selected to be 4.1-4.9, wherein the number of the impeller blades 6 is 8-16, preferably 12, and the consistence coefficient of the impeller is 4.24, which is obviously lower than that of the conventional impeller design. The small number of the blades of the impeller and the small chord length of the blades can reduce the tensile stress borne by the wheel disc 5, enhance the strength and the service life of the rotor, and are favorable for reducing the weight and the manufacturing cost of the impeller.
The impeller blade 6 is formed by stacking at least three flow surface blade profiles 7 distributed along the blade height direction along the stacking line 8 of the impeller blade 6 along the blade height direction, and the flow surface blade profiles 7 are two-dimensional blade profiles on an M-theta space and represent three-dimensional space curves under a Cartesian coordinate system. The flow surface blade profile 7 is composed of a blade back profile line 71, a blade basin profile line 72, a camber line 73, a blade profile leading edge 74 and a blade profile trailing edge 75, the flow surface blade profile 7 is designed in a symmetrical blade profile mode, namely, on an M-theta space, perpendicular lines are respectively drawn towards the blade back profile line 71 and the blade basin profile line 72 along any point on the camber line 73, and the distances between the two perpendicular lines are equal. The back contour 71, the cone contour 72, and the camber line 73 may be represented by Bezier curves, B-spline curves, or any other arbitrary, smooth, continuous curve. In addition, the vane front edges 74 of the flow surface vane profiles 7 at different vane heights of the impeller vanes 6 are kept consistent in height in the radial direction, so that the bending moment of an impeller inlet can be reduced, the strength and the service life of the impeller are improved, and the processing difficulty and the detection complexity of the impeller can be reduced.
In addition, the impellerFlow surface profile axial chord length l of the blade 6 at the blade root 63 h Axial chord length l of flow surface profile at blade tip 64 t The ratio of (A) to (B) is 1.05-1.25, so that the average chord length of the surface of the blade is reduced, the low-consistency design is facilitated, and the mixing loss at the outlet of the impeller is controlled.
In order to reduce the loss of the angle of attack, in the present invention, the inlet blade angle α of the impeller blade 6 from the blade root 63 to the blade tip 64 increases linearly in the direction of the blade height, the inlet blade angle α of the blade root 63 is between 0 ° and 5 ° according to the difference of the inflow angle of the incoming flow, and the inlet blade angle α of the blade tip 64 is between 5 ° and 10 ° according to the difference of the inflow angle of the incoming flow. By adopting the design, the non-uniformity of the incoming flow inlet angle in the radial direction caused by the increase of the load can be adapted, the air flow separation caused by the positive attack angle is reduced, the flow is smoother, the total pressure loss of the flow is reduced, and the performance of the engine is improved.
Meanwhile, the average chord length L of the surface of the blade ms And a decrease in the number of blades Z, such that the airflow velocity at the blade tip 64 increases, the load increases, resulting in an increase in the tip clearance gap leakage flow driven by the lateral pressure differential as the airflow velocity at the blade tip 64 increases, especially at locations closer to the trailing edge 62 of the impeller blade, with more intense leakage losses. To reduce the problem of increased leakage losses due to reduced blade solidity, a "C-shaped" blade flow angle distribution at the exit section of blade tip 64 is used. That is, the blade profile of the blade tip 64 is distributed in a C-shape along the flow direction, the airflow angle changes more smoothly in the chord length region of 0-10%, the airflow angle changes rapidly in the chord length region of 10-80%, and the blade angle remains substantially unchanged in the chord length region of 90-100%. Through the design, the airflow acceleration capacity of the 80 percent chord length area of the blade tip part 64 is increased, the blade tip load at the outlet is reduced, the leakage flow caused by the transverse pressure gradient in the blade tip clearance near the outlet tail edge of the centripetal impeller is reduced, and the blade tip leakage is reducedLeakage loss and turbine efficiency are improved.
In addition, the stacking line 8 is defined as a line connecting the leading edge starting points of the camber lines 73 of all the flow surface blade forms 7. In order to control the radial load distribution of the blade, the low-energy fluid in the boundary layer is reduced to be accumulated on the suction surface of the blade and the root 63 of the blade, and the flow loss of the end region is reduced, the accumulation line 8 is offset by a certain included angle theta along the blade height direction and the circumferential direction, and the included angle theta between the accumulation line 8 and the circumferential direction is between-10 degrees and 10 degrees.
The centripetal impeller provided by the invention effectively reduces the number of blades of the impeller, the axial size and the weight by adopting the design of the low-consistency impeller, simultaneously reduces the blade tip clearance leakage and the secondary flow loss at the end area by adopting the reasonable blade profile design, realizes the high-load and low-consistency design of the centripetal impeller on the premise of ensuring the turbine performance, improves the power-weight ratio of an engine, is beneficial to reducing the maximum stress of the disc center of the wheel disc 5, and improves the strength and the service life of the impeller.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A turbine guider is applied to a centripetal turbine with a large expansion ratio,
the guide device comprises a guide device outer ring (1), a guide device inner ring (2) and a plurality of guide device blades (3), wherein the guide device outer ring (1) and the guide device inner ring (2) are symmetrically arranged around an engine axis, an annular airflow channel is formed between the guide device outer ring (1) and the guide device inner ring (2), the annular airflow channel extends for a certain length along the axial direction of a centripetal turbine inlet and then is bent for 90 degrees to form airflow channels distributed along the radial direction, the guide device blades (3) are uniformly arranged in the annular airflow channel along the circumferential direction at the same interval angle, the ratio of the height of an inlet straight section of each guide device blade (3) to the height of the inlet of each blade is designed to be 1.15-1.25, and the radius ratio of the inlet and outlet of each guide device blade (3) is 1.1-1.3.
2. The turbine nozzle as set forth in claim 1,
the outer ring (1) of the guide has an outwardly convex bulge-like structure at the position when turned axially to the radial direction, so as to ensure that the annular passage area from the guide inlet to the leading edge (31) of the guide vane is gradually expanded.
3. The turbine nozzle as set forth in claim 1,
a cold air cavity (37) is arranged in the guide vane (3), and a plurality of cold air slits (35) are arranged at the tail edge (32) of the guide vane in a 10-90% vane height area.
4. The turbine nozzle as set forth in claim 3,
the position of the blade basin surface (33) of the guide blade (3) from the tail edge (32) of the guide blade to 16.5% of the whole chord length is the starting position of the cold air slit (35).
5. The turbine nozzle as set forth in claim 3,
the guide vane (3) adopts a uniform section vane profile design.
6. The turbine nozzle as set forth in claim 1,
the guide vane (3) adopts a contracting vane profile design, and the throat width of the vane is positioned between the trailing edge (32) of the guide vane and the throat position of the vane back surface (34) of the adjacent vane.
7. The turbine nozzle as set forth in claim 6,
the bending angle delta of the tail edge of the guide vane (3) is between 1 and 16 degrees.
8. The turbine nozzle as set forth in claim 1,
the maximum profile thickness C of the guide vane (3) max The ratio to the chord length b of the blade is 0.17.
9. The turbine nozzle as set forth in claim 8,
thickness R of the trailing edge (32) of the guide vane t Is 0.1C max 。
10. A high expansion ratio centripetal turbine, characterized in that a turbine nozzle according to any one of claims 1-9 is used.
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| CN113062775A (en) * | 2021-04-19 | 2021-07-02 | 中国航发湖南动力机械研究所 | Low-consistency centripetal impeller and centripetal turbine with high expansion ratio |
| CN113790175B (en) * | 2021-09-22 | 2024-05-24 | 大连海事大学 | Radial air inlet chamber for improving guide vane wake vortex |
| CN115111003B (en) * | 2022-05-24 | 2024-09-24 | 中国航发湖南动力机械研究所 | Turbine guider matched with large bent pipe |
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| CN102606221A (en) * | 2011-01-14 | 2012-07-25 | 通用电气公司 | Curved cooling passages for a turbine component |
| CN104533533A (en) * | 2011-06-29 | 2015-04-22 | 三菱日立电力系统株式会社 | Supersonic turbine moving blade and axial-flow turbine |
| CN109751090A (en) * | 2017-11-03 | 2019-05-14 | 清华大学 | Guide vane and nozzle ring with it |
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| US8075259B2 (en) * | 2009-02-13 | 2011-12-13 | United Technologies Corporation | Turbine vane airfoil with turning flow and axial/circumferential trailing edge configuration |
| US10465529B2 (en) * | 2016-12-05 | 2019-11-05 | United Technologies Corporation | Leading edge hybrid cavities and cores for airfoils of gas turbine engine |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102606221A (en) * | 2011-01-14 | 2012-07-25 | 通用电气公司 | Curved cooling passages for a turbine component |
| CN104533533A (en) * | 2011-06-29 | 2015-04-22 | 三菱日立电力系统株式会社 | Supersonic turbine moving blade and axial-flow turbine |
| CN109751090A (en) * | 2017-11-03 | 2019-05-14 | 清华大学 | Guide vane and nozzle ring with it |
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